The invention relates to a turbine ring assembly for a turbine engine, which assembly comprises a ring support structure and a plurality of single-piece ring sectors made of ceramic matrix composite material.
The field of application of the invention is in particular that of gas turbine aeroengines. Nevertheless, the invention is applicable to other turbine engines, e.g. industrial gas turbines.
Ceramic matrix composite materials (CMCs) are known for conserving their mechanical properties at high temperatures, thereby making them suitable for constituting hot structural elements.
In gas turbine aeroengines, improving efficiency and reducing certain polluting emissions has led to seeking operation at ever-higher temperatures. When a turbine ring assembly is made entirely out of metal, it is necessary to cool all of the elements of the assembly, and in particular the turbine ring, which is subjected to the hottest streams. Such cooling has a significant impact on the performance of the engine since the cooling stream that is used is taken from the main stream through the engine. In addition, the use of metal for the turbine ring puts a limit on potential increases of temperature in the turbine, even though such increases would nevertheless make it possible to improve the performance of aeroengines.
That is why it has already been envisaged to use CMCs for various hot portions of engines, particularly since CMCs present the additional advantage of density that is lower than that of the refractory metals that have traditionally been used.
Thus, making turbine ring sectors as single pieces of CMC is described in particular in Document US 2012/0027572. Each ring sector comprises an annular base having an inside face that defines the inside face of the turbine ring and an outside face from which there extend two tab-forming portions with ends that are engaged in housings of a metal ring support structure.
The use of CMC ring sectors makes it possible to reduce significantly the ventilation needed for cooling the turbine ring. Nevertheless, although each ring sector is fastened individually to the ring support structure, holding the sectors in position relative to one another can sometimes be problematic since it can be difficult to control the shape of the turbine ring made up of the sectors. Furthermore, another problem resides in the stresses generated by the imposed movements. In addition, sealing between the gas flow passage on the inside of the ring sectors and the outside of the ring sectors remains a problem at the edges of adjacent ring sectors.